-I brought my external hard drive (for my PC, NTFS) over to a buddies to grab some files.
-He has 2 macs.
-1st mac couldn't write - only read.
-2nd mac had no trouble writing a small test file so..
-I dragged and dropped a FOLDER containing many other folders and subsequently many files (side question, is this where I went wrong? If i had copied only the files themselves would it have avoided whats to come?)
-I didn't receive any prompts or errors so I thought nothing of... the folders and files copied just fine.
-Get back to my PC and plug it in.
-My computer recognizes there is a drive, however its not labeled as normal - only "Local Disk (F:)"
-Upon trying to interact in anyway (doubleclick to explore, right click to view properties) it will crash file explorer. Same with trying to access it thru cmd.
-I found and ran testdisk and was able to see drive as \\.\PhysicalDrive3
-Selected Intel/PC
-Analyzed - Quick Search
-Found the partition (the only partition is the whole drive)
-Says Structure: OK, Partition *HPFS - NTFS
-I hit "P" to list files

-THANK GOD my files were still there (I was afraid perhaps his mac decided to format without telling me)

-This is where I get stuck as well as nervous about trying things I've never done... heres what I've done thus far...

-I found a thumb drive formatted in FAT32 and copied the newly added folders/files I had got from my friends mac to that drive with the intention/plan to simply erase the folders that caused the hard drive to crap out from the external HD. (would this have even worked?) The copied files are working fine on my thumb drive.. no errors
-What I did not know is that testdisk cannot delete files (ok, it does say delete all files in the partition table, but the drive is only 1 large partition so that is the opposite of what I want)
-Testdisk is the only way I've been able to access the drive in anyway, I can breathe easy knowing the drive didn't get wiped and it's possible to copy those files somewhere else buttttt ...
-I don't have enough free disk space (especially in FAT32 or something compatible) to copy the whole drive somewhere else, reformat the *$#%ed drive, and move it all back. (would that just re$**%! the drive anyway?)
-I've never dealt with data recovery/ filesystems beyond wiping hard drives and fresh installing an OS

Please help!!!

Do I rebuild the filesytem? Will/can that result in any data lossage? Am I even asking the right questions?

If you want to try an inplace repair, run "cmd" (right click run as administrator) and "chkdsk /f f:"
But it's probably safer to get a new disk to hold the recovered files and use testdisk, Advanced, List to copy the files.